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Palpography for Vulnerable Plaque Detection. Mortality. 60 - 80% of all myocardial infarctions are caused by ruptured vulnerable plaques. What is a Vulnerable Plaque. Constantinides P 1966; J Atheroscler Res, 6, 1 Schaar et al. EHJ 2004. Thin Cap Fibroatheroma (TCFA).
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Palpography for Vulnerable Plaque Detection
Mortality 60 - 80% of all myocardial infarctions are caused by ruptured vulnerable plaques
What is a Vulnerable Plaque Constantinides P 1966; J Atheroscler Res, 6, 1 Schaar et al. EHJ 2004
Principle of IVUS palpography • Different tissues deform in a different way • Deformation of tissue changes the ultrasound signals (rf-signals)
Echosignals of deformed tissue A B C D DAB DCD undeformed DAB - DA’B’ A’ B’ C’ D’ @ DA’B’<DAB DC’D’ DCD deformed Soft Hard
F HARD F SOFT
Sensitivity and Specificity in vitro Sensitivity =88% Specificity = 89% Schaar JA, et al. Circulation 2003
Sensitivity and Specificity Relation between strain and tissue components 3,0 3.0 2,5 2.5 2,0 2.0 1.5 1,5 1.0 1,0 Strain (%) Strain (%) .5 ,5 0,0 0.0 26 3 12 13 n = none minor medium heavy none minor medium heavy Smooth muscle cells Macrophages p < 0.0001 p < 0.006 Schaar JA, et al. Circulation 2003
Sensitivity and Specificity Inverse relation between strain and cap thickness y = 236/x R2 = 0.68 p < 0.0001 Based on: Loree HM, et al. Circ Res 1992; 71: 850 - 8 Schaar JA, et al. Circulation 2003
Sensitivity and Specificity in vitro Schaar JA, et al. Circulation 2003
= 100 μm cap thickness Schaar et al, Eur Heart J 2003, Herz 2005
3 D Palpography Depth 1% 0 % Angle
Previous Current
Previous Current
Interpretation ROtterdam Classification (ROC)
In vivo incidence of high strain spots Symptoms vs. number of high strain spots n = 55 coronary arteries 19 stable angina 18 unstable angina 18 post MI 3.0 p < 0.0001 2.5 p = n.s. p < 0.001 2.0 High Strain Spots 1.5 1.0 SEM 0.5 SD 0.0 stable unstable post MI Symptom Schaar et al, Circulation 2004
In vivo incidence of high strain spots Relation to CRP 3,0 2,5 2,0 CRP µg/dL 1,5 1,0 0,5 R2 = 0.60 0,0 none one two three Number of high strain spots Schaar et al, Circulation 2004
Conclusion Palpography • Vulnerable plaque in vitro • High Strain spots in vivo correlate with symptoms and inflammation markers • Reproducible in vivo (animal, human) • Follow up is possible (IBIS, IBIS II, PROSPECT)